laravel eloquent join 如何使用 scope ？

Question

有两个表

表 user

id	name
1	tom
2	jerry

表 friend

id	user_id	support_id
1	1	1
2	1	2

表 support

id	name	can_fly
1	bird	1
2	dog	0

三个 Model

class User extends Model{
    public function friends()
    {
        return $this->hasMany(Friend::class);
    }
}

class Friend extends Model{
    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function support()
    {
        return $this->belongsTo(Support::class);
    }
}

class Support extends Model{
    public function scopeFly($query)
    {
        return $query->where('can_fly', 1);
    }
}

我想实现如下 sql，意义为 获取 tom 所有会飞的朋友 关系

select * from friend 
    inner join support on friend.support_id = support.id
    inner join user on friend.user_id = user.id
    where user.id = 1
    and where support.can_fly = 1

我这样写，但后边的不会写了，求解。

$user = User::find(1);
$user->friends()-> {how to inner join support} -> {how to use support's scopeFly}

Answer 1

你可以在 Friend 模型中定义一个新的本地作用域，结合 with 和 whereHas 方法实现：

class Friend extends Model
{
    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function support()
    {
        return $this->belongsTo(Support::class);
    }

    public function scopeWithFlySupport($query)
    {
        return $query->whereHas('support', function ($query) {
            $query->fly();
        });
    }
}

现在，你可以在查询中用 withFlySupport 作用域：

$user = User::find(1);
$friendsWithFlySupport = $user->friends()->withFlySupport()->get();